The present invention generally relates to a process for the production of edible protein filaments from a cooked protein source material.
Food scientists have long been interested in using a wide variety of protein sources to produce primary food products which resemble meat. Among the most sought for alternatives have been processes for converting protein sources such as oilseed meals, flours, cereal proteins and microbial proteins into a more acceptable protein food product, particularly those that would resemble meat in texture. This impetus has resulted in the development of a wide variety of techniques to produce textured protein food products resembling meat. A common technique has been the wet spinning process disclosed in U.S. Pat. No. 2,682,466 to R. A. Boyer. The wet spinning process generally produces protein fibers by extruding a plurality of fine streams of an aqueous solution of protein into an acid, chemical coagulating bath. The protein coagulates into fine fibers which are then collected and treated to form an edible textured protein product. Other methods of producing textured protein products resembling meat have included a shred-like protein product by heat coagulation of undenatured protein as diclosed in U.S. Pat. No. 3,047,395 to Rusoff, et al.
Since the development of these early processes for forming textured protein products from a variety of edible protein sources, expanded, textured products have since been produced by the extrusion of a proteinaceous source through an environment of elevated pressure and temperature into an environment of substantially lower pressure, with resultant puffing and expansion thereof. The expanded cellular product has textural characteristics upon rehydration with water which is very similar to a cooked piece of meat. Extrusion techniques for the production of expanded cellular protein product, especially those derived from oilseed meals, are described in U.S. Pat. No. 3,488,770 and U.S. Pat. No. 3,496,858.
More recently, a process for the production of textured protein filaments from a wide variety of protein sources has been disclosed, and provides a method of producing textured protein without a requirement for special equipment, thereby avoiding a large capital expenditure in order to commercialize the process. The noted process has involved the heating of a slurry of a proteinaceous material by conducting the slurry through a heat exchanger at a proteinaceous solids level of between about 0.3 and 35 percent by weight, under pressure, and heating the same for a sufficient period of time so that elongated filaments can be caused to separate from the remaining constituents of the slurry. The heated slurry is thereafter continuously removed from the heat exchange zone through a back pressure creating orifice wherein discrete elongated filaments and the remaining constituents of the slurry are discharged into a collecting zone and separated. The protein filaments thereby formed are useful in making a wide variety of food products and may be conveniently incorporated with conventional primary meat sources to form food products having improved aesthetic appeal, flavor and economy. Processes of the above type which may be employed to form this unique elongated protein filament, include those described in U.S. Pat. Nos. 3,662,671, 3,662,672, 3,821,453 and Reissue No. 28,091. The noted patents describe a wide variety of proteinaceous materials which may be used to produce the fibers pursuant to the process disclosed therein, including vegetable protein such as soy or other oilseed meals, animal protein such as albumen or casein, microbial protein, such as those derived from yeast or petroprotein. The process disclosed therein has proven to be an effective solution to the attendant problems associated with other prior art processes for the production of textured protein products from protein sources.
In spite of the tremendous advantages which the above identified processes for the production of the elongated protein filaments provide; nevertheless, these and other prior art processes were entirely dependent upon the presence, at least in part, of a protein source which would commonly be considered as "uncooked" or had not been subjected to any degree of heating or chemical treatment to thereby render the same in an undenatured state. It was generally determined that in most of the prior art processes for the texturization of protein, at least some percentage of uncooked protein was necessary to permit the formation of a textured product. Therefore, in spite of the success of the above identified processes for the production of protein products resembling meat, there has still existed a need for an effective means of texturizing a protein source such as an entirely "cooked" meat or a protein source which has been effectively heated or in a substantially denatured state prior to texturization.
Up to this particular point in time, the only alternative insofar as using a cooked protein source, in forming a textured protein food product, and the like, was to employ additives or binding agents with which the cooked meat could be combined and thereby compressed into a roll or placed in a casing to result in an integral structure for the noted product. The resulting product, however, has a very artificial appearance, and the protein source during subsequent treatment and handling thereof, lost any textural qualities which a consumer would normally associate with a primary protein source, such as meat, which had been freshly cooked. It would, therefore, be highly desirable if a process could be devised which would permit the restructuring or texturing of "cooked" protein sources which have heretofore been considered unusable in protein texturizing processes of the prior art.
The instant invention obviates the above identified difficulties, and provides a process for the restructuring or texturing of "cooked" protein sources to form desirable and edible food products. The process disclosed herein represents an improvement on the processes generally set forth in U.s. Pat. Nos. 3,662,671, 3,662,672, Reissue No. 28,091 and U.S. Pat. No. 3,821,453 by defining a certain set of critical conditions including critical temperature limitations for the production of elongated protein filaments from a "cooked" rather than an "uncooked" protein source. For a complete understanding of the instant invention and for one to be able to determine the protein sources to which it applies, it was felt to be necessary to define the protein sources to which the present invention is deemed to be operative, and hence the term "cooked." This is necessary since this term is capable of a very subjective definition, depending upon individual desires and tastes. In this regard, it was determined pursuant to the instant invention that a proper definition of this term could only be made by examining the individual constituents of the protein source, and the resultant effect of heating, chemical treatment or cooking upon these constituents and, therefore, arrive at an acceptable definition of the noted term based upon the effects of cooking on various individual constituents of the protein source. In this regard, it was determined that the well recognized technique of gel electrophoresis provided a particularly effective means of separating and identifying the individual constituents of the meat source thereby permitting an evaluation of the effect of heating or cooking on these constituents. In this manner, the definition of the term "cooked" as it is employed in the instant invention was arrived at. Insofar as the present invention, the term "cooked" is defined as that stage of heating or treatment when the intensity of electrophoretic bands of the particular meat source having a relative mobility of between about 0.13 and 0.32 has been substantially reduced as measured by polyacrylamide gel electrophoresis. An electrophoretic pattern of uncooked or raw meat sources, contains a substantial percentage of unknown components, probably heat sensitive enzymes within the noted relative mobility range of the electrophoretic pattern. The application of heat, chemical treatment and accordingly, the degree of cooking, will effect the relative intensity of these enzymes or whatever particular materials correspond to these bands, and a substantial reduction in intensity of these bands would, therefore, represent that point in time when a protein source is "cooked." The present invention is, therefore, intended to apply to the use of "cooked" protein sources as is defined by the above terminology, since by this definition the term "cooked" can be used to distinguish those protein sources of the present invention from those employed in texturization processes of the prior art. As previously noted, these prior art texturization processes required at least the partial presence of a raw or uncooked protein source.
It is, therefore, an object of the instant invention to provide a process for the production of edible protein filaments from cooked meat sources.
It is a further object of the instant invention to provide a process for the production for elongated protein filaments from a protein source which is economically feasible and reliable to practice on a commercial scale.
It is also an object of the present invention to define a process for the production of edible protein filaments from a cooked meat source as represented by a critically defined set of conditions in order to produce a protein filament with a high degree of aesthetic appeal resembling a primary meat product.
It is also an object of the present invention to provide an elongated protein filament which is usable in a wide variety of food products.